Vaccination: Doubters don't let facts get in the way

Science-based messages urging parents to vaccinate their children fall on deaf ears, even as rare and deadly diseases make a comeback. Keith Kloor reports.

Pro-vaccination messages are least persuasive among parents with the most negative attitudes. Some health care experts say it's a matter of talking to individual parents.

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Many parents dread taking their baby for the scheduled immunisation jabs. But for some parents, concerns about vaccination are so great that their children are never vaccinated. When there is plenty of scientific evidence against these concerns, you might think all it takes is education. Not so, according to a study published in the journal Pediatrics in March. “We found that a pro-vaccination message was least persuasive among parents with the most negative attitudes towards vaccines – the group of greatest public health concern,” the authors wrote.

This is unwelcome news to the Centers for Disease Control (CDC) in the US. The costs to the community of not vaccinating are dire, with once rare and deadly diseases such as whooping cough making a comeback. In recent years the CDC has sought to allay parents’ concerns about the safety of vaccines with scientific information posted on its website. For instance, one of its messages discusses the “carefully performed scientific studies” that have found no link between the measles, mumps, rubella (MMR) vaccine and autism, as is believed by a minority of parents. Another message is the cautionary tale of a baby’s life-threatening bout with measles following exposure to an unvaccinated, infected child.

Trying to correct false claims and beliefs about vaccines with scientific evidence is at best likely to fail, at worst to reinforce negative attitudes. – iStock

In theory these messages based in science should persuade parents to inoculate their children against preventable diseases. To find out if the theory worked in practice, the authors of the study used a detailed questionnaire to survey the responses of parents who had read information produced by the CDC and other health agencies.

The researchers found the education did nothing to increase parents’ intention to vaccinate their future children. In fact, in the one third of parents who were identified as the most sceptical, the evidence-based material actually hardened their views. The study also found that the story about a child with measles “increased beliefs in serious vaccine side effects”. Trying to correct false claims and beliefs about vaccines with scientific evidence is at best likely to fail, and at worst likely to reinforce parents’ concerns.

The findings are not all that surprising. The “backfire effect” is a term coined in the mid-2000s by political scientists Brendan Nyhan (of Dartmouth College) and Jason Reifler (of University of Exeter), two of the authors on the current study. This occurs when information designed to correct beliefs ends up reinforcing a pre-existing mindset or belief. Cognitive scientists call it “motivated reasoning”: people seek out information that confirms their beliefs and push away information that threatens them. It’s not just true for vaccines; studies on attitudes to climate change and evolution also bear this out.

'As parents or patients, we all want our questions to betaken seriously and answered well.'

But with vaccines, the problem has important implications for public health. What message might work to persuade this group of parents? For some health care experts, it’s a matter of talking to individual parents, and listening.

That’s the approach championed by Julie Leask, a trailblazing public health researcher at the University of Sydney. Her communication strategy for parents who resist vaccination “encourages questions and employs a guiding rather than directing style”. How might this strategy play out between a paediatrician and a vaccine-hesitant parent? Instead of rushing to correct wrong information, Leask stresses that it is important to first understand what a parent’s vaccine concerns are. “As parents or patients, we all want our questions to be taken seriously and answered well,” Leask says. “It is normal to want to know about the few risks of vaccination, along with what sorts of diseases they are protecting babies and children against.”

This guiding style, what is known as “motivational interviewing”, builds trust and rapport between a parent and a paediatrician, Leask says. But the approach also has pitfalls. “I think doctors engaging with sceptical members of the public could be a useful approach,” says Nyhan. “But it’s important not to give parents a false impression by dwelling for too long on concerns that they may have.”